104-Maximum-Depth-of-Binary-Tree.swift

//
//  104-Maximum-Depth-of-Binary-Tree.swift
//  algorithm
//
//  Created by Lugick Wang on 2020/3/30.
//  Copyright © 2020 Lugick Wang. All rights reserved.
//

import Foundation

public class TreeNode {
    public var val: Int
    public var left: TreeNode?
    public var right: TreeNode?
    public init(_ val: Int) {
        self.val = val
        self.left = nil
        self.right = nil
    }
}


class Solution {
    
    func maxDepth(_ root: TreeNode?) -> Int {
        if root == nil {
            return 0
        }
        let left = maxDepth(root?.left)
        let right = maxDepth(root?.right)
        return max(left, right) + 1
    }
}